@max When you evaluate only TrueQ[x > 0] outside Assuming you get False since TrueQ may have only logical values and while you haven't assigned any value to x it has to return False. Assuming[cond, eqn] is supposed to work with equations or mathematical functions which return numerical values. Nevertheless when you set e.g. x=5 then Assuming[x > 0, TrueQ[x > 0]] will return True unlike e.g. Assuming[x < 0, TrueQ[x < 0]] just because TrueQ is a logical operator not an equation and x has an assigned value.
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ArtesMar 26 '12 at 23:48

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